This paper presents a new design and analysis of a haptic interface for simulation of needle intervention. The target procedure is lung biopsy among various needle interventions. In order to train a lung biopsy, there are two main training points which are the decision of needle insertion angle and realization of the current needle position. Thus, the training simulation for lung biopsy is required for the haptic rendering for 3 DoF force components especially in the limited visual feedback as a lung biopsy.
There are many haptic interfaces for various needle interventions. However, there exists only one haptic interface for lung biopsy from our research team in the world. This haptic interface for lung biopsy considers 5 DoF which are 2 translational motions for skin manipulation, 2 rotational DoF for changing needle angle and 1 DoF needle insertion. There are two main parts among these to provide 3 DoF force feedback which consist of the linear and the rotational parts. The linear part has a virtual needle and linear guide to embody the linear mechanism of a needle to provide 1 DoF linear force feedback to the operator. The force feedback for 1 DoF needle insertion is provided by the gear-driven mechanism. However, the gear-driven mechanism leads the haptic interface with a bad backdrivability, backlash and loud noise when a needle is inserted or extracted.
The rotational part has a structure with 4 bar linkage and parallel rotation mechanism to provide 2 DoF rotational force feedback and to able moving a needle on spherical orientation. However, there is only a 1 DoF strain gauge load cell on the linear part. Then, it cannot measure 2 DoF rotational force correctly.
From these limitations of the haptic interface for simulation of lung biopsy, a novel power transmission mechanism for 1 DoF insertion force feedback is developed by using tendon-drive mechanism. Additionally, 2 DoF force sensing system is developed for rendering 2 DoF bending moment to the operator. These designs can provide 3 DoF force feedback clearly and improve the backdrivability with reduced noise.